Proposal: improve the Data.Tree API

[João Cristóvão]

Hi Ivan,

>> then what about the arguably better name `size`?
> Huh, I thought we already had that.

We do?
If there is consensus I would then add `size` with the arguably more
efficient implementation:
size :: Tree a -> Int
size = getSum . F.foldMap (const $ Sum 1)

> * An Ord instance (achievable via standalone deriving, though this isn't
ideal)

Agreed.

> * Functions to take/drop so many levels of the tree (take is
> relatively easy; drop would result in a Forest).

Similar to treeprune in
http://hackage.haskell.org/package/hledger-lib-0.22.1/docs/Hledger-Utils.html#v:subtreeat?

> mirror :: Tree a -> Tree a
> mirror (Node a ts) = Node a . reverse $ map mirror ts

I don't have strong feeling about this one, but if more people see as
useful, why not...

João


2014-02-24 11:38 GMT+00:00 Ivan Lazar Miljenovic <ivan.miljenovic at gmail.com>
:

> On 24 February 2014 22:17, Tobias Florek <haskell at ibotty.net> wrote:
> > hi,
> >
> >> But to be honest, I don't have strong feelings about this, I'm willing
> >> to drop this particular function (length) from the proposal, if there is
> >> no consensus.
> >
> > then what about the arguably better name `size`?
>
> Huh, I thought we already had that.
>
> Some things I missed when I last used Data.Tree:
>
> * An Ord instance (achievable via standalone deriving, though this isn't
> ideal)
>
> * A function to take the mirror-image of a tree (name not that important):
>
> mirror :: Tree a -> Tree a
> mirror (Node a ts) = Node a . reverse $ map mirror ts
>
> * Functions to take/drop so many levels of the tree (take is
> relatively easy; drop would result in a Forest).
>
>
> >
> > cheers,
> >  tobias florek
> >
> >
> > _______________________________________________
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>
>
>
> --
> Ivan Lazar Miljenovic
> Ivan.Miljenovic at gmail.com
> http://IvanMiljenovic.wordpress.com
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